It is well known that the weaving process necessarily involves the use of loom apparatuses and processes whereby the warp yarns are controlled to form sheds through which the weft is inserted, beat up by the loom reed and then locked into position by warp reversal. The warp yarns are controlled by means of heddles mounted within harness frames, the frames being moved between upper and lower positions by suitable driving means. In the most simple weaving arrangement there are only two harness frames, each frame controlling a preselected number, usually half, of the warp yarns. To produce more intricate weaving patterns, larger numbers of harness frames are used so that the number of warp yarns controlled by any given frame is less than the number that would usually be controlled in the simple two harness construction.
It is also known that loom harnesses may be moved between upper and lower positions by either positive or negative drive means. The positive driving method means that the harnesses are actively moved in two directions by a positive driving mechanism whereas in the negative method the harnesses are driven positively in one direction and then returned to the original position by means of biasing springs, or equivalent motivating elements. Most commonly, in loom negative dobby applications, the frames are moved to the upper position by means of a loom dobby that is connected to the upper rail of each frame. The return biasing means is appropriately connected to the bottom rail of each frame. Thus, when the dobby moves a frame to the upper position, the lower biasing means is tensioned so that it can return the frame to its lower position upon relaxation of the dobby pull.
Although various loom negative dobby systems generally have been used widely and found useful for many applications, there exist inherent limitations. Specifically as loom speed has been increased to achieve greater loom productivity it has been necessary to increase the strength of the biasing means. This increase in strength has, in turn, caused the harness frames to be placed in extreme tension and the result has been bowing of the frame, with the consequent undesirable side effects. Strengthening of all of the interrelated parts has meant increases in the sizes of the parts and these increases in sizes have restricted the number of loom harnesses that could be used on any given loom. Also, change or repair of a loom harness has caused excessive down time of the loom because the connections to the harnesses were not capable of being easily disconnected.